the large boards are the regulator boards, 50x70mm, and came to 9E (about 13$) per board.

The small ones that you see in the picture are bridge-pcbs for the high voltage high current Schottky-diodes with ultra-low forward voltage - discussed here . With these little pcbs you can build a full bridge rectifier using 4 of these Schottky-diodes and I will offer a small number of them here.

If you're interested in the small Schottky-bridge pcbs, they're 25x25mm, drop me an email!